Radio-frequency glow discharges in methane gas: modelling of the gas-phase physics and chemistry
Radio-frequency glow discharges in methane gas: modelling of the gas-phase physics and chemistry
复制标题
甲烷气体中的射频辉光放电：气相物理和化学建模
DOI：
10.1088/0022-3727/27/4/020
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
G. Turban
中科院分区：
文献类型：
--
作者：
E. Gogolides;C. Buteau;A. Rhallabi;G. Turban
建立了甲烷排放流体模型，并将其与简单的气相化学动力学模型相结合。其目的是为了更好地了解带电物种的动力学，以及它们与甲烷等离子体中的气相动力学的相互作用。在流体模型中使用群体数据作为输入，该模型预测了射频周期内离子和电子密度、电场和电离率作为空间和时间的函数。结果表明，由于脱离，甲烷中的负离子密度约为电子的10-2量级，观察到类似于正电气体的电容放电行为。研究了电极间距(2~6 cm)、气体压力(80mTorr~1 Torr)和射频电流(2.2~3.4 mA cm~(-2)0.06~0.15 W cm~(-2))的影响，并与实验数据进行了比较。时间平均、空间分辨的电子密度和能量、CH2和CH3解离的截面集合，以及关于电子能量分布函数形式的假设，随后被用作简化的一维气相动力学模型的输入。该模型预测了CH2和CH3的空间分布，与实验数据吻合较好。
A methane discharge fluid model is developed, and subsequently combined with a simple gas-phase chemical kinetics model. The aim is to provide better understanding of the charged species dynamics, and their interaction with the gas-phase kinetics in a CH4 plasma. Swarm data are used as input in the fluid model, which predicts the ion and electron densities, electric fields and ionization rates as a function of space and time in the radio-frequency period. Results show that, due to detachment, the negative ion density in CH4 is of order 10-2 that of electrons; a capacitive discharge behaviour is observed analogous to that of an electropositive gas. The effects of electrode spacing (2-6 cm), gas pressure (80 mTorr to 1 Torr) and radio-frequency current (2.2-3.4 mA cm-2 0.06-0.15 W cm-2) are studied and compared successfully with experimental data. The time-averaged, spatially-resolved electron density and energy, the set of cross sections for CH2 and CH3 dissociation, together with an assumption about the form of the electron energy distribution function, are subsequently used as input in a simplified one-dimensional gas-phase kinetic model. The model predicts the CH2 and CH3 spatial profiles, which compare well with experimental data.